What makes a macro lens truly "macro"?

[alanosaur]

I've been trying to figure this out for the past week with no luck, so hopefully one of you guys can help explain it to me.

People around me keep saying that I should buy a macro lens if I want to do food photography or some really cool close-up nature photography, but when I look at the macro lenses available I have trouble understanding how they're any much better than the other lens of similar specs.

For example, the 60mm f/2.8 macro vs. the 50mm f/1.8 or the 17-55mm f/2.8.

What's the difference??

Aside from difference in focal length, it seems to me that the 50mm has a better f-stop, and the 17-55mm allows for better wide-angle shots. So what would make me want to buy the 60mm in this scenario? Is there truly a unique macro feature that exists on the 60mm that neither the 50mm nor the 17-55mm doesn't have?

[Vascilli]

..This is a thing I understand but can't explain.. (Because I don't actually know how it works either)

..So I'll let someone else do it.

[KimLeece]

I'd guess it's minimum focus distance, and magnification - 1:1 or better. That means that the projected image on the sensor is the same size, or bigger, than what is being captured.

[jeromego]

I've been trying to figure this out for the past week with no luck, so hopefully one of you guys can help explain it to me.

People around me keep saying that I should buy a macro lens if I want to do food photography or some really cool close-up nature photography, but when I look at the macro lenses available I have trouble understanding how they're any much better than the other lens of similar specs.

For example, the 60mm f/2.8 macro vs. the 50mm f/1.8 or the 17-55mm f/2.8.

What's the difference??

Aside from difference in focal length, it seems to me that the 50mm has a better f-stop, and the 17-55mm allows for better wide-angle shots. So what would make me want to buy the 60mm in this scenario? Is there truly a unique macro feature that exists on the 60mm that neither the 50mm nor the 17-55mm doesn't have?
a 60 2.8 macro is a dedicated macro lens where you can shoot object life size 1:1

[twofruitz]

Simply the ability to focus with a 1:1 magnification ration.

Most other lens will get to about 1:6ish which can not make small objects large enough.

Another trait of macro lenses is their sharpness and image quality, which cannot be had generally until the L series range.

[DreDaze]

For example, the 60mm f/2.8 macro vs. the 50mm f/1.8 or the 17-55mm f/2.8.

What's the difference??


the minimum focus distance(MFD) of the 50 1.8 is 0.45m...meanwhile the MFD of the 60mm macro is .2M...the MFD of the 17-55 is .35m

the shorter focus distance allows you to fill more of the viewfinder with the subject...you can achieve 1:1 magnification, which i believe means the object is the size of the sensor on your camera

the magnification of the 50 alone is 1:7

[milorad]

I'll elaborate a little on the 1:1 thing, since nobody's really gone into any detail on this.

Lets say you're shooting with a full-frame camera. The full-frame is 35mm right? well a macro lens will allow you to shoot a 35mm object from close enough so that it fills your 35mm frame entirely.

35mm isn't very big... trying to fill your camera's frame with an object that size is impossible on a non-macro lens because typically it's unable to focus closely enough.

Now, macro lenses come in various focal lenths, meaning that the wider angle macro you get, the phycically closer your lens has to be to the object, to achieve 1:1 magnification. A 180mm macro for instance, will let you shoot from a much more comfortable distance away from your subject, than a 60mm macro will.

You may not care, unless you're shooting spiders... except that a little more distance usually makes it easier to light your subjects.

[alanosaur]

Okay that clears up some confusion. But I'm not shooting on full-frame. I've got a 40D, so how does the 1.6x FOVCF affect the 1:1 magnification on the macro lens?

@everyone: thanks for all the quick replies!

[egordon99]

1:1 Macro means that an object the size of the sensor (whatever sensor/film you're using) completely fills the frame.

So since a crop sensor is smaller than FF, you can actually photograph a smaller object than with FF.

[dontblink]

1:1 Macro means that an object the size of the sensor (whatever sensor/film you're using) completely fills the frame.

So since a crop sensor is smaller than FF, you can actually photograph a smaller object than with FF.

No, it just means that a smaller object fills the frame. Crop sensors are smaller than full frame sensors, and because of that they change the field of view of lenses, but they do NOT magnify.

[gasrocks]

Many Macro lenses do not go to 1:1, only 1/2 life size. Macro lenses are meant to be used at MFD, they are sharp there. Most other lenses are least sharp at MFD.

[PiRho]

Okay that clears up some confusion. But I'm not shooting on full-frame. I've got a 40D, so how does the 1.6x FOVCF affect the 1:1 magnification on the macro lens?

@everyone: thanks for all the quick replies!
it doesn't affect the 1:1 magnification at all.

No, it just means that a smaller object fills the frame. Crop sensors are smaller than full frame sensors, and because of that they change the field of view of lenses, but they do NOT magnify.
yup. what he said.


think of it like this. you have an image that you are capturing, it is a small piece of paper measuring 24mm x 36 mm (ie full frame) with a true macro lens** the entire piece of paper is visible in the shot, and nothing surrounding the paper. with your 40D, the sensor is 14.8mm x 22.2mm which means that shooting the same peice of paper from the full frame example, you will only see the middle 14.8 x 22.2mm of the scene. in essence all we did was change the 1:1 into a mathamatically equivalent 1.4:1.4

ok now I think I prolly confused you LOL sorry. in other words in true macro you will always be able to at least fill your screen(100% viewfinder) with something the same size as your cameras sensor.

if this just totally confused you... ignore it and read what others said :confused:





** Many companies advertise that a lens is 'macro' when it does not actually achieve 1:1 ratio. rather that it just has 'close focus'.

[yogestee]

Simply the ability to focus with a 1:1 magnification ration.

Most other lens will get to about 1:6ish which can not make small objects large enough.

Another trait of macro lenses is their sharpness and image quality, which cannot be had generally until the L series range.

Since when?? What about other makes such as Nikkor, Zeiss, Zuiko and others??

[egordon99]

Isn't that what I said? In simplified terms, on a FF you can photograph a quarter and have it fill the frame. On crop, you could do the same with a penny(just guessing on the sizes of the coins......) Hence you can photograph a smaller object (at 1:1)

No, it just means that a smaller object fills the frame. Crop sensors are smaller than full frame sensors, and because of that they change the field of view of lenses, but they do NOT magnify.

[egordon99]

Tell that to my Canon 85mm f/1.8 and Sigma 30mm f/1.4 :confused:

Simply the ability to focus with a 1:1 magnification ration.

Most other lens will get to about 1:6ish which can not make small objects large enough.

Another trait of macro lenses is their sharpness and image quality, which cannot be had generally until the L series range.

[Kanonenfutter]

Alanosaur, your 40D's sensor is 22mm wide. Get a metric ruler, all the lenses you can get ahold of, and see which lenses let you fill the entire frame from left to right with ruler notches amounting to exactly 22mm, in perfect focus. That's 1:1.

The 60mm and 100mm and 180mm macro lenses will do that. The 60mm lens will have to be very close to the subject (maybe a bit too close for comfort with insects etc.), the 100mm lens will be quite a bit further away, and the 180mm lens further yet.

Aside from comfort level and practicality re. proximity to subjects, these distances and focal lengths will also affect the DOF (blur in BG etc).

The 60mm and the 100mm are "faster" (more light-sensitive) at f/2.8 at their widest openings, the 180mm is f/3.5.

These lenses are very fine for other uses, too, for example the 100mm f/2.8 macro lens is popular as a portrait lens.

Hope this helps.

[KimLeece]

The 60mm is built for the crop sensor - it's an EF-S lens.

[Sfordphoto]

a true macro will make images 1:1, meaning lifesize. meaning that if you took the sensor out and put it next to an object...the object would be that big on the sensor, i'd imagine.

[KarlosDaJackal]

So to sum up what everyone is saying.

If your mostly interested in doing extreme close-ups of plants/insects/whatever get a dedicated macro lens. It will work at 1:1 and you always have the option of backing up a bit.

If your mostly interested in general photography but would like to get close sometimes, get a general purpose lens with a macro option, this will not get you quite as close as a macro lens would, but its better than nothing, 1:2 is pretty damn big, 1:3 is still close.

True macro is 1:1, but if you think of it, there are a lot of things bigger than a 22mm or 35mm sensor you might want to take macros shots of. For instance a profile view of a big dragonfly will not fit on a 35mm sensor, so you'd end up shooting it a 1:2 anyway, same with lots of flowers 1:1 might be too tight.

[John_B]

alanosaur,
Welcome to POTN :)

Here are two photos to show the difference between a 1.6 camera (10D) and a Full Frame camera (5D) both shooting same subject at 1:1 life size macro

10D with 100mm f/2.8 macro at 1:1
http://johnbdigital.com/macro/lens_compare/10d_100mm.jpg

5D with 100mm f/2.8 macro at 1:1
http://johnbdigital.com/macro/lens_compare/5d_100mm.jpg

[DAMphyne]

The field of view is certainly bigger with the FF.
If you crop the FF to the size of the crop sensor, you will find that they are the same, 1:1 is 1:1.
The crop picture of the currency is just enlarged.

[Lester Wareham]

I've been trying to figure this out for the past week with no luck, so hopefully one of you guys can help explain it to me.

People around me keep saying that I should buy a macro lens if I want to do food photography or some really cool close-up nature photography, but when I look at the macro lenses available I have trouble understanding how they're any much better than the other lens of similar specs.

For example, the 60mm f/2.8 macro vs. the 50mm f/1.8 or the 17-55mm f/2.8.

What's the difference??

Aside from difference in focal length, it seems to me that the 50mm has a better f-stop, and the 17-55mm allows for better wide-angle shots. So what would make me want to buy the 60mm in this scenario? Is there truly a unique macro feature that exists on the 60mm that neither the 50mm nor the 17-55mm doesn't have?

By strict definition a macro lens should be capable of life size magnification unaided. In practice this is just a lot more convenient than extension tubes, particularly in the field.

More than that, a macro lens will be well corrected for lens aberrations at close distances, ie sharper with less chromatic aberrations, it should also have good flatness of field at close distances which ordinary lenses do not.

This is why macro lenses are typically about a stop slower than the equivalent ordinary lens to allow the designer to accommodate these additional requirements.